In many industrial applications, chemical reagents and compositions are required to be supplied in a high purity state, and specialized packaging has been developed to ensure that the supplied material is maintained in a pure and suitable form, throughout the package fill, storage, transport, and ultimate dispensing operations.
In the field of microelectronic device manufacturing, the need for suitable packaging is particularly compelling for a wide variety of liquids and liquid-containing compositions, since any contaminants in the packaged material, and/or any ingress of environmental contaminants to the contained material in the package, can adversely affect the microelectronic device products that are manufactured with such liquids or liquid-containing compositions, rendering the microelectronic device products deficient or even useless for their intended use.
As a result of these considerations, many types of high-purity packaging have been developed for liquids and liquid-containing compositions used in microelectronic device manufacturing, such as photoresists, etchants, chemical vapor deposition reagents, solvents, wafer and tool cleaning formulations, chemical mechanical polishing compositions, color filtering chemistries, overcoats, liquid crystal materials, etc.
One type of high-purity packaging that has come into such usage includes a rigid, substantially rigid, or semi-rigid overpack containing a liquid or liquid-based composition in a flexible liner or bag that is secured in position in the overpack by retaining structure such as a lid or cover. Such packaging is commonly referred to as “bag-in-can” (BIC), “bag-in-bottle” (BIB) and “bag-in-drum” (BID) packaging. Packaging of such general type is commercially available under the trademark NOWPAK from Advanced Technology Materials, Inc. (Danbury, Conn., USA).
Preferably, a liner comprises a flexible material, and the overpack container comprises a wall material that is substantially more rigid than said flexible material. Rigid or semi-rigid overpack of the packaging may be formed (for example) of a high-density polyethylene or other polymer or metal, and the liner may be provided as a pre-cleaned, sterile collapsible bag of a polymeric film material, such as polytetrafluoroethylene (PTFE), low-density polyethylene, medium-density polyethylene, PTFE-based laminates, polyamide, polyester, polyurethane, or the like, selected to be inert to the material (e.g., liquid) to be contained in the liner. Multilayer laminates comprising any of the foregoing materials may be used. Exemplary materials of construction of a liner further include: metalized films, foils, polymers/copolymers, laminates, extrusions, co-extrusions, and blown and cast films. Liner-based packaging of such general type is commercially available under the trademark NOWPAK from Advanced Technology Materials, Inc.
In use of liner-based packaging to dispense liquids and liquid-based compositions, the liquid or composition is dispensed from the liner by connecting a dispensing assembly including a dip tube or short probe to a port of the liner, with the dip tube being immersed in the contained liquid. Fluid (e.g., gas) pressure is applied to the exterior surface of the liner (i.e., in the space between the liner and a surrounding overpack container), to progressively collapse the liner and thereby force liquid through the dispensing assembly for discharge to associated flow circuitry to flow to an end-use tool or site. Such operation may be called liner-based pressure dispensing. Use of a liner to contain a liquid to be dispensed prevents direct contact with pressurized gas arranged to exert pressure against the liner.
A simplified schematic of a conventional liner-based package 60 is provided in FIG. 1A, showing a liner 62 having (surrounding) an interior volume containing a liquid 68, with the liner 62 disposed within an overpack container 61. An interstitial space 63 is provided between the liner 62 and the overpack container 61, and is in fluid communication with a pressurized gas source 65. Addition of pressurized gas to the interstitial space 63 compresses the liner 62 to cause liquid 68 to flow through a diptube 64 out of the container to a process tool or other point of use 66.
Headspace (extra air or gas at the top of a liner) and microbubbles present a significant process problem for liquid dispensing from liner-based packages, such as in flat panel display (FPD) and integrated circuit (IC) manufacturing facilities. Headspace gas may derive from the filling operation, in which the package is less than completely filled with the liquid. Less than complete filling of the package may be necessary in order to provide a headspace as an expansion volume to accommodate changes in the ambient environment of the package, such as temperature changes that cause the liquid to expand during transport of the package to a location where the package will be placed in dispensing operation.
While maintenance of headspace in a liner-based package may be desirable during package transport, such headspace may be detrimental to fluid dispensing and/or use. Gas from the headspace may become entrained in the liquid being dispensed from a liner-based pressure package and produce a heterogeneous, a multi-phase dispensed fluid stream that is deleterious to the process or product for which the dispensed liquid is being utilized. Further, the presence of gas from the headspace in the dispensed liquid can result in malfunction or error in operation of fluid flow sensors, flow controllers, and the like.
A related problem, incident to the use of packages containing liquid compositions, is permeation or in-leakage of gas into the contained liquid and solubilization and bubble formation in the liquid. In the case of liner-based packages, gases exterior to the liner may permeate through the liner (e.g., through slightly permeable film materials, seams between liner panels, and/or pinholes formed in liner panels) into the contained liquid. Where liner-based packages are utilized for pressure dispense operation, the pressurizing gas itself, e.g., air or nitrogen, may permeate through the liner material and become dissolved in the liquid in the liner. When the liquid subsequently is dispensed, pressure drop in the dispensing lines and downstream instrumentation and equipment may cause liberation of formerly dissolved gas, resulting in the formation of bubbles in the stream of dispensed liquid, with consequent adverse effect analogous to those resulting from entrained headspace gas. It would therefore be desirable to remove headspace gas prior to initial dispensation. It would also be desirable to permit continued removal of liberated gas after liquid dispensation has commenced. It would further be desirable to accomplish gas removal rapidly while reducing the potential for microbubble formation.
In the manufacture of semiconductor products and other microelectronic products, the presence of bubbles, even those of microscopic size (microbubbles), can result in an integrated circuit or flat-panel display being deficient or even useless for its intended purpose. It therefore is imperative for all extraneous gas to be removed from the liquid utilized for the manufacture of such products.
In use of a typical liner-based package, the package is pressurized and a venting valve is opened to allow headspace gas to flow out of the liner. After headspace gas is exhausted, liquid enters the headspace gas discharge line, a gas venting valve is closed, and another valve is opened to dispense only liquid in a liquid discharge line. When the package signals an empty detect condition, e.g., by monitoring of pressure of the dispensed fluid, and detection of a drop in the pressure as a function of time, the connector or other coupling device joined to the vessel containing the liner can be removed from the exhausted vessel, and placed on a fresh (e.g., full) container, to provide for continued dispensing operation. Due to presence of liquid in the headspace removal line, a timer may be used to bypass the liquid sensor until headspace gas arrives again. Thereafter, liquid reenters the vent line and the sensor is “re-activated” with the timer to close the vent valve. Such arrangement, however, is susceptible to failure modes involving occurrence of the following events: (i) the timer is not set correctly and transmits a false signal indicating that the headspace has been removed; (ii) headspace varies from one filled package to another, and settings that are selected for one package are not appropriate for another, so that the headspace gas is not correctly removed; (iii) bubbles present in the headspace gas vent line create a false indication of headspace gas removal; and (iv) remaining (previously present) liquid in the headspace vent line can give a false indication of headspace gas removal.
Additionally, in the storage and dispensing of liquids and liquid-based compositions from liner packages, it is desirable to manage the dispensing operation so that the depletion or approach to depletion of the dispensed material is detected so that termination of a downstream operation, or switchover to a fresh package of material, is able to be timely effected. Reliability in end-stage monitoring of the dispensing operation, and particularly in detection of an empty or approaching empty condition, therefore enables optimum utilization of liner packages, and is a desired objective for design and implementation of such packaging. It can be difficult to reliably and economically detect an empty condition or approach to empty condition indicative of exhaustion of liquid from a package or reservoir for dispensation to a downstream process. Upon completion of detection, a second source of liquid is preferred to be automatically switched over, thereby eliminating any additional downstream operational concerns. For example, a switchover reservoir adapted to supply fluid deriving from said pressure dispense package may be utilized for dispensing when a pressure dispense package is emptied or nearly emptied of said fluid.
Another problem associated with packages from which liquids are dispensed for industrial processes such as manufacture microelectronic device products, relates to the fact that the liquids in many cases are extraordinarily expensive, as specialty chemical reagents. It therefore is necessary from an economic perspective to achieve as complete a utilization of the liquid from a package as possible, so that no substantial residual amount of liquid remains in the package after the dispensing operation has been completed. For such reason, it is desirable to monitor the dispensing operation in a manner that permits determination of the endpoint of such operation. There is a continuing effort in the art to provide efficient endpoint detectors that minimize the amount of liquid residuum in the package.
Certain problems with liner-based dispensing packages have been addressed by systems and methods disclosed in International Patent Application Publication No. WO/2007/146892 (“the '892 publication”), which is assigned to Advanced Technology Materials, Inc., shares several common inventors with the present application, and is hereby incorporated by reference herein. The '892 publication discloses highly integrated connectors that provide the following utilities: liquid dispensing, headspace gas removal, pressure relief, pressure measurement, and reservoir gas/liquid level control (i.e., via sensing and valving). The accompanying FIG. 1 (which is adapted from FIG. 20A of the '892 publication) provides a cross-sectional view of at least a portion of such a connector 1 including an integrated reservoir 16 and a sensor 55 proximate to an interface between liquid 58 and gas (i.e., disposed above the liquid 58) within the reservoir 16, to sense a condition in which a gas pocket has accumulated along an upper portion of the reservoir 16, to permit gas to be periodically and automatically expelled from the reservoir 16 during dispensing operation. Although not fully illustrated in FIG. 1, the connector 1 includes a probe (in which a central conduit 6 is defined) arranged to extend downward into a liner. The central conduit 6 extends in the middle of a container and/or liner (not shown) and the reservoir 16 disposed within the body 24 of the connector 1. The central conduit 6 has a central bore accommodating upward gas/liquid flow, and an open upper end 10 allowing the upflowing gas/liquid during dispensing operation to overflow the upper end 10 and issue into the reservoir 16. A pressurized gas supply line 3 is used to supply pressurized gas to a space between a liner and an overpack container to promote dispensation of the liquid contents of the liner into the connector 1. A pressure sensing line 21 and pressure sensor 22 are arranged to sense pressure in the central conduit 6. A gas conduit 18, which is in fluid communication with the reservoir 16 at an upper portion thereof, is communicatively coupled to an actuatable gas outlet valve 34. A corresponding liquid outlet conduit 19 is in fluid communication with the reservoir 16 at a lower portion thereof and is communicatively coupled to an actuatable liquid outlet valve 30.
Although integrated reservoir systems disclosed in the '892 publication achieve their intended purpose, various considerations have demonstrated unmet needs for modifications or enhancements to such systems.
Liner-based pressure dispensing containers are often installed in dedicated material dispensing enclosures or cabinets with numerous other fluid lines and fluid control components. Presence of an integrated reservoir and other components requires presence of significant space (volume) above a pressure dispensing container, and also requires multiple electrical and fluid connections to be made within that space. It would be desirable to reduce volumetric requirements immediately proximate to pressure dispensing containers, and also reduce the number of electrical and fluid connections that need to be made immediately proximate to such containers.
In case a liner within a pressure dispense package according to the '892 publication should fail, it may be difficult or impossible to continue dispensation of a liquid composition with the liner due to flow of gas from a pressurized gas inlet through the central conduit (e.g., central conduit 6 as illustrated in the accompanying FIG. 1), to the exclusion of liquid flow through such central conduit. It would be desirable to provide for continued flow of liquid through a connector of a liner-based pressure dispense assembly even if the integrity of the liner should be compromised.
Sole reliance on gravimetric separation between liquid and gas within a reservoir such as disclosed in the '892 publication may not provide ample separation in case very high viscosity liquids and/or high liquid dispensing rates are used. That is, depending on the liquid viscosity and flow rate in a gravimetric reservoir separation system, upward motion of gas bubbles in a reservoir (i.e., toward a gas outlet arranged at an upper portion thereof) may not be sufficiently fast to overcome downward motion of liquid in the reservoir (i.e., toward a liquid outlet arranged at a bottom portion thereof), such that some bubbles may be undesirably entrained in flow of liquid through the liquid outlet associated with the reservoir. It would be desirable to ensure that gas bubbles are not entrained in liquid dispensed to a point of use over a wide range of liquid viscosities and liquid flow rates.
Prior methods of joining a diptube to a mating (e.g., recess-defining) structure have occasionally led to tube cracking. Certain joining methods have involved tube flaring and other techniques, which are also labor intensive. It would be desirable to accommodate mating of a diptube to a mating structure while avoiding the foregoing issues.
When dispensing highly opaque liquids (e.g., pigmented color filter materials and used for coating flat panels in the manufacture of display monitors, and similar fluids), conventional systems and methods for detecting presence or absence of liquid may be insufficient, since optical measurement techniques may be ineffective and capacitance measurement techniques may be insufficiently sensitive and/or reliable as applied to such liquids. It would be desirable to enhance reliability of detecting opaque fluids for dispensing of same to desired points of use, such as manufacturing process tools for flat panel displays.
When dispensing fluid from a liner-based pressure dispense package including an overpack container containing a thin film-based liner defining an interior volume arranged to contain source material (including liquid), gas trapped within folds of a liner may be released during dispensation and may be dissolved in the source material. That is, conventional liners may embody two-dimensional designs (e.g., including front and back panels, optionally including side and/or end panels) that are peripherally bonded to one another) that are not conformal to the shape of an associated overpack container, and gas may be trapped in folds of such a liner when the liner is inflated and filled. Release of such gas during pressure dispensing enables such gas to be dissolved in source material. When the source material is saturated with gas, the source material or container (containing source material) must be replaced to avoid dispensation of source material containing gas bubbles. Such replacement may be necessary long before source material is exhausted from the pressure dispense container, thereby wasting source material and potentially reducing utilization of a process tool while a pressure dispense container is changed. Based on testing and simulation, Applicants have been determined that the maximum amount of fold gas at the upper limit should not surpass 500 ml for a 200 liter liner.
FIG. 10 shows dissolved gas saturation pressure (in Pascals) versus time (in days) for simulations modeling gas released from folds during pressure dispense of fluid from seven different 200 liter collapsible film-based container liners (e.g., simulations including a liner with 0 cm radius fold containing 0 ml of fold gas, a 1 cm radius fold containing 17 ml of fold gas, 2 cm radius fold containing 133 ml of fold gas, a 3 cm radius fold containing 447 ml of fold gas, 4 cm radius fold containing 1061 ml of fold gas, a single Z-fold configuration, and a double Z-configuration, respectively). The volume of each bubble is calculated assuming the bubble is under atmospheric pressure, while the radius of each bubble is calculated assuming the bubble is subjected to 30 psi dispense pressure. As shown in FIG. 10, a double Z-fold liner configuration tends to trap more gas (resulting in higher gas saturation pressure) than a single Z-fold liner. Based on the simulation represented in FIG. 10, liquid source material becomes saturated (e.g., with 500 ml of) fold gas following dispensation of about 88% of the source material.
Applicants have determined that fold gas is not released from folds of a pressure dispensing liner until very late in the dispensation process. This means a liner with relatively high rigidity and poor conformance to an overpack container will have folds and be susceptible to the dissolved gas. FIG. 11 shows the release of fold gas with respect to time for a first liner with a single Z-fold configuration (lower curve) and for a second liner with a double Z-fold configuration (upper curve). Such figure shows that a larger amount of fold gas is trapped within a liner having a double Z-fold configuration than in a liner having a single Z-fold configuration. FIG. 11 shows that a substantial amount of fold gas remains within a liner during the last 25 percent of the dispense process. The issue is also exacerbated by the high ratio of gas to remaining source material within the liner near the end of the dispense process (when the majority of the liquid source material has been depleted from the liner).
Whether or not in conjunction with presence of fold gas, presence of any pin holes or larger opening (i.e., a breach) in a liner tend to allow ingress of pressurization gas into the liner and gas headspace, thereby hastening attainment of (undesirable) saturation of source material with gas.
It would be desirable to manage the effects of fold gas and the effects of a failed liner in pressure dispensing of source material. It would be desirable to increase the percentage of dispensed source material without reaching the gas saturation level (e.g., to enable dispensation of a very high percentage (e.g., >98% or >99%) of source material before a gas-saturated condition is reached) in order to reduce waste of source material and extend the time between replenishment of source material containers.
The art therefore continues to seek improvements in dispensing packages, dispensing systems, dispensing methods, and associated sensing apparatuses.